Various embodiments of the present disclosure relate to an electronic device and a method for wireless charging in the electronic device.
A mobile terminal, such as a portable phone or a PDA (Personal Digital Assistant), uses rechargeable battery. In order to charge such a battery, electric energy is supplied by a separate charging device that plugs into the mobile device, or otherwise mates the contact terminals of the mobile device to contact terminals of the charging device. However, this type of charging scheme exposes the contact terminals on the mobile device and/or the charging device to the environment. Accordingly, the contact terminals may get contaminated by foreign matter, thereby interfering with charging the battery. Additionally, the exposed contact terminals on the mobile device may make it harder to make the mobile device water resistant.
Wireless charging, or contactless charging, technology has been developed and used for a number of electronic devices. Such wireless charging technology uses wireless power transmission and reception. The wireless charging technology allows a battery to be charged by merely putting a mobile device, such as a cell phone, on a charging pad without connecting the portable phone to a separate charging device. Wireless charging technology is used for many devices currently, including for wireless electric toothbrushes and wireless electric shavers. It is expected that wireless charging technology will advance significantly as electric cars become more common.
Presently, main interests in wireless charging technology have been with the inductive coupling scheme, the resonance inductive coupling scheme, and the radio wave (e.g., RF/microwave) radiation scheme. Up to the present, the inductive coupling scheme has been used for the most part. When power is transferred by the inductive coupling scheme, referred to in this disclosure as the induction scheme, current in a primary coil generates a magnetic field, and that magnetic field induces current in a secondary coil. Power transmission using inductive coupling has excellent energy transmission efficiency. However, the primary and secondary coils must be very close to each other for efficient energy transfer.
The resonance inductive coupling scheme, referred to in this disclosure as the resonance scheme, is a type of inductive coupling scheme where both the transmitter and the receiver have circuits tuned to a specific frequency. Professor Soljacic at MIT demonstrated this wireless charging system in 2005 by transferring power to an electronic device several meters away using Coupled Mode Theory. The resonance scheme uses the concept of resonance frequency, where resonance frequency is a characteristic of all objects. An object may preferentially generate or receive energy at its resonance frequency. For example, when a tuning fork is struck, it will vibrate at its resonance frequency. A wine glass near the turning fork with the same resonance frequency will absorb the acoustic energy of the vibrations generated by the tuning fork until the wine glass shatters. Similarly, a power transmitter using the resonance scheme generates a magnetic field of a specific frequency. Energy is transferred via that magnetic field only when there is a receiving device with receiving circuitry that has that resonance frequency. Due to larger distances between the transmitting device and the receiving device, the resonance scheme may have lower energy transmission efficiency than the induction scheme.
In recent years, however, experiments for wirelessly transmitting power from several tens of meters using microwave have been successful at home and abroad. Thus, it is expected that in the near future, all the electronic products can be wirelessly charged without wires anywhere anytime.
Various wireless charging standards have been proposed by Alliance for Wireless Power (A4WP) for the resonance scheme, Wireless Power Consortium (WPC) for the induction scheme, and Power Matters Alliance (PMA) for the resonance scheme and the induction scheme. If different products are released using different standards, it may become inconvenient for the user with respect to usability and compatibility.
Accordingly, in order for one electronic device to support the functions of a plurality of standards, a variety of additional elements may be required, or parallel configurations may need to be made to support the respective standards.
Furthermore, in an electronic device providing wireless charging, the circuits or systems constituting a transmitter and a receiver are different from each other. Thus, if the transmitter and the receiver are implemented together in an electronic device, a transmitter and a receiver may need to be provided for each standard that is supported.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.